Transformer-Coupled Loopback Test for Differential Mixed-Signal Dynamic Specifications

• Published in: IEEE transactions on instrumentation and measurement 2011-06, Vol.60 (6), p.2014-2024
• Main Authors: Byoungho Kim, Abraham, J A
• Format: Article
• Language: English
• Subjects: Analog and mixed-signal testing; Built-in self-test; built-in self-test (BIST); built-off self-test (BOST); Capacitance; design for test (DfT); differential signal circuit test; Dynamics; Electric circuits; Faults; Harmonic analysis; Harmonic distortion; loopback test; Masking; Multiplexing; Noise; Power system harmonics; Radio frequencies; Radio frequency; Specifications; Studies; Transformers
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2011.2113128

Loopback tests for a differential mixed-signal device under test (DUT) have rarely been attempted since any imbalance introduced by design-for-test (DfT) circuitry on differential signaling delivers an imperfect sinusoidal wave to the DUT input or output, thereby degrading the DUT performance. In addition, this methodology inherently suffers from fault masking. These problems trigger low test accuracy and serious yield loss. This paper presents a novel methodology for the efficient prediction of individual DUT dynamic performance parameters with a radio-frequency (RF) transformer in loopback mode to overcome the imbalance of DfT circuitry and the fault masking. Cascaded RF transformers with different multiplicative weights are selected in three combinations by a multiplexer to create three separate loopback responses. These responses are used to characterize the DUT dynamic performance. Hardware measurement results show that this approach can be effectively used to predict the specifications of a DUT.